Adjustable arc



March 7, 1933. wl HlNCKELMANN 0 1,900,500

ADJUSTABLE ARC FiledhApril 14, 1931 Patented Mar. 7, 1933 UNITED STATES WERNER HINCKELMANN, or PHILADELPHIA, ranlxsYLvANIAY ADJUSTABLE Ane.v

Application led. April 14,

This invention relates to an adjustable arc for the use of draftsmen in drawing arcs of large radii, particularly arcs which are considerably beyond the range `of practical compasses.

It is a primary object of the invention to provide a flexible ruling edge arranged so as to be adjustably flexed to form different arcs, which arcs are substantially circular in form. To this end a linkage is provided connected to the ruling edge at various points so that the form of the ruling edge in various positions of adjustment is closely maintained.

It is a further object of the invention to provide a device of this character which may be graduated directly in terms of the radii of the arcs to which it is adjusted.

These and other objects of the invention relating particularly to details of construction will be apparent from the following description read in conjunction with the accompanying drawing in which: s

Fig. 1 is a plan View of the device shown 25 in full lines in position with the ruling edge straight and partially in dotted lines to illustrate the flexure of the linkage to produce an arcuate form of ruling edge; and

Fig. 2 is a fragmentary section taken `as indicated by the line 2 in Fig. 1.

The adjustable arc comprises a flexible backing member 2 to the face of which is secured a suitable member il of Celluloid or the like to provide the ruling edge. Pivoted to the member 2 and extending perpendicularly therefrom at about its center is a guiding rod 6 threadedV at its inner end for engagement with a nut 8. Sldable on the rod 6 are a number of slides 10, the outermost slide being specifically designated as 18. Pivoted to these slides 10 andlSfand also to nut 8 are certain links of a composite linkage illustrated at 12 and composed of a large number of small links arranged to form a plurality of rhombic aggregations, certain of the boundary links being pivoted to the member 2 as indicated at 16. Preferably upper and lower sets of these links are provided as clearly indicated in Fig. 2 there being corresponding upper and lower links,

i931.Vv serial no.l 523,925. I

the two sets: being provided primarily to obtain the necessary rigidity. It will be ob'- vious, of course,` that but one set need'be used. -The linksV are pivoted to each other Y by pins 14 which 'may connect thecOrre- 55 spending pivotpoints vof the'upper and lower sets. v i

The slide 18 is' lprovided vwith-a swivel connection, as at 21, with a nut 20 which isv threaded on the enlarged outer end22 ofthe *'60 member 6.' This outer end terminates in a suitable handle 24. Preferably the enlargedv end is cut flat on one side and provided with a scale 26 which may be' graduatedi'n an l Suitable units,` preferably inthe radii of the arcs producible by fiexure of the ruling edge. From the above it will be clear that when the nut` 20 is rotated on the screw 22 rit will movelengthwise of the guiding member 6 f thereby producing a deformation of' the '70 linkage to the eXtreme illustrated in dotted lines in Fig. l, to whichl deformation will correspond a certain radius of curvature ofV the ruling edge.

A zero adjustment is provided by reason of the nut 8threaded on the innerend of the guiding member 6. While in the ordinary Y operation of the device the member is not .turned relatively to the member 2,"it may *Y be turned relativelythereto to provide zero adjustment. When so turnedy the memberl 8 moves inwardly or outwardly producing suitably slight flexure of the linkage. VIn this way the device may be set so a reading of the scale indicating infinite radius will correspond to astraight ruling edge.

Preferably the zero adjustment referred to takes place* during ytheassembly of the instrument to secure absolute correlation be- .90 tween the positions ofthe ruling yedge and the scale which is laid `out mathematically to bear proper proportionalitytothecurve. After assembly of the instrument', the nut 8` v may be fastened to the rod by drillinga hole G through both and riveting the'mtogether.

It will be clear that vnumerous variations in the invention may be made without denparting from the spirit thereof as defined in thefollowingA claims.

2. An adjustable arc comprisingaflexibleI plurality of rhombic aggregations, whereby movements of the slides on the guiding member effect leXure of the ruling edge.

In testimony of Which invention, I have hereunto set my hand, at Philadelphia, on this 10th day of April, 1981.

WERNER HINCKELMANN.

h 1 ruling edge, a guiding member connected i thereto, a member movable along the guiding member, ahnut threadedon theguiding member andv connected to the `movable member, andI a linkage connecting the ruling `edge and movable member, whereby movement of the movable member effects lexure of the ruling edge, said linkage including links forming a ieticulated array of quadrilaterals joined to the ruling edge'at a pluralityof points. y

3. An adjustable are .comprising a flexible ruling edge, a guidingA member connected thereto, a member movable along the guiding member, a nut threaded on the guiding member and connected to the movable member, and a linkage connecting the ruling edge andinovable member, whereby movement of the. movable member eects leXure of the` ruling edge, said guiding member be- .ing provided with a scale for cooperation with the movable memberindicative of the curvature of the ruling edge in Various posii tions oi' adjustment, said linkage including `links forming a reticulated array of quadrilaterals joined to the ruling edge at a pluj rality of points. Y

4. An adjustable arc comprising a flexible ruling edge, a guiding vmember connected thereto, a member movable along the guiding member, a nut threaded on the guiding member and connected to the movable member, and a linkage connecting the ruling edge and movable member, whereby movement of the movable member effects fleXure being provided with a scale for cooperation of the ruling edge, said guiding member With the movable member indicative of `the i curvature of the ruling edge in various positions of adjustment, and said guiding membe'r being adjustable relative to the ruling edge for` zero adjustment, said linkage in'- cluding links forming a reticulated array 01" quadrilate'rals joined to the ruling edge at 'a plurality of points.

` An adjustable arc comprising a flexible i i ruling edge, a guiding member connected to the mid-portion of the ruling edgeand eX'- tending perpendicularly thereto, slides on the guiding member, and a linkage comprising an array of links pivoted to the ruling edge, the slides, and each other forming a 

